The so-called ink-jet recording method has come into practical use in which droplets of a recording liquid containing a water-soluble colorant, e.g., a direct dye or an acid dye, are issued from a minute ejection orifice to conduct recording.
With respect to the recording liquid, it is required not only to be stably ejectable over a long time period and to rapidly fix to recording papers for general business use, e.g., paper for PPCs (plain-paper copiers) such as electrophotographic paper, and fanfold paper (continuous paper for computers, etc.), to give a print in which the printed characters are of good quality, that is, the printed characters are free of blurring and have clear contours, but also to be excellent in storage stability of the recording liquid. Therefore, solvents usable in the recording liquid are severely restricted.
With respect to colorants for the recording liquid, on the other hand, they are required, for example, not only to have sufficient solubility in the solvents that are restricted as described above to thereby enable the recording liquid to be stably ejected over a long time period and be stable even in long-term storage and to give printed images having high density and excellent water resistance and light resistance, but also to be produced easily and free from any problem in safety. However, it has been difficult to satisfy these many requirements simultaneously.
Although various techniques (e.g., JP-A-55-144067, JP-A-55-152747, JP-A-57-207660, JP-A-58-147470, JP-A-62-190269, JP-A-62-190271, JP-A-62-190272, JP-A-62-250082, JP-A-62-246975, JP-A-62-257971, JP-A-62-288659, JP-A-63-8463, JP-A-63-22867, JP-A-63-22874, JP-A-63-30567, JP-A-63-33484, JP-A-63-63764, JP-A-63-105079, JP-A-64-31877, JP-A-1-93389, JP-A-1-210464, JP-A-2-140270, JP-A-3-167270, JP-A-3-200882, etc.) have hence been proposed, a colorant has not been developed which sufficiently meets the performance requirements of the market and is easy to produce. (The term "JP-A" used herein means an "unexamined published Japanese patent application.)